Open Rights Group and Tor have established that UK mobile networks such as Vodafone, O2 and 3 are filtering UK users' access to Tor's primary website (meaning the HTTP version of the Tor Project website, rather than connections to the Tor network) on pre-paid contractless accounts.
Tor helps people stay anonymous online. Some examples of how it has been used include those trying to avoid oppressive state censorship in places such as Iran, through to abuse victims in the UK. There is a post by Jacob Appelbaum with more technical details about the blocking on UK mobile networks over at the Tor blog.
These mobile networks' filters are supposed to be tools through which parents can manage their children's access to the Internet. O2 provide a tool to check whether a URL is blocked under their filtering system. Searching for 'torproject.org' tells us it is blocked because it falls into the category of 'anonymiser'. (Orange also say that they block content that falls into the 'anonymiser' category - but it does not seem that Tor is blocked on Orange.) It's unlikely that mobile operators are targeting Tor, and more likely that anonymisation tools generally are filtered.
It is not clear why services such as Tor have been included in filtering systems. It's clear that mobile operators need to look again at what sites they are blocking and why, especially when those blocks include important and legitimate tools such as Tor.
We initially established that Tor was blocked initially through our new tool blocked.org.uk. You can help us monitor how filtering on mobile networks works by reporting when you come across incorrectly applied blocks.
Problems with mobile Internet filtering
These problems would be less of an issue if it was clear to users when filtering applied to their account, how to turn the filter off, and how to report mistakes. But this isn't the case.
Phone companies 'filter' the mobile Internet because they don't know whether their phones are being given to or used by children and young adults. This happens by default in most cases. The concern is that if young people have unfettered access to the Internet they will stumble upon undesirable material. Filtering is usually turned 'on' by default.
Mobile Internet filtering systems can often block access to the wrong content, for example because content is categorised incorrectly or simply because the blocks are applied too broadly.
We created a website recently that helps people report when this 'over-blocking' happens. In the last couple of weeks, we have received around 30 reports of inappropriate blocks to sites ranging from bars and restaurants through to personal blogs and pictures. This is denying businesses access to their market, consumers to services they want and restricting people's ability to freely access information online.
One of the first cases we came across was of a church being blocked by O2 - with the person running the church having serious problems getting the site unblocked.
Such stories help demonstrate many of the problems with overly broad blocking:
Open Rights Group will be meeting with mobile operators over the next few weeks to talk about making sure that they can both help parents manage their children's mobile Internet use and avoid clumsy implemented filtering. Some are better at aspects of this than others (Orange provide an overview of the categories they block, for example.) But none implement a transparent and clear policy that puts users in charge.
We hope to have a good and constructive discussion about the pitfalls and how to tackle them; we have some pretty simple 'asks' that should help address many of the problems:
We'll be posting about our discussions with mobile operators as they happen.